Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe ME/CFS patients, 2020, Van Campen, Rowe, Visser

[Sly Saint]

Reductions in Cerebral Blood Flow Can Be Provoked by Sitting in Severe Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Patients

Abstract
Introduction: In a large study with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) patients, we showed that 86% had symptoms of orthostatic intolerance in daily life and that 90% had an abnormal reduction in cerebral blood flow (CBF) during a standard tilt test. A standard head-up tilt test might not be tolerated by the most severely affected bed-ridden ME/CFS patients. Sitting upright is a milder orthostatic stress. The present study examined whether a sitting test, measuring cerebral blood flow by extracranial Doppler, would be sufficient to provoke abnormal reductions in cerebral blood flow in severe ME/CFS patients. Methods and results: 100 severe ME/CFS patients were studied, (88 females) and were compared with 15 healthy controls (HC) (13 females). CBF was measured first while seated for at least one hour, followed by a CBF measurement in the supine position. Fibromyalgia was present in 37 patients. Demographic data as well as supine heart rate and blood pressures were not different between ME/CFS patients and HC.

Heart rate and blood pressure did not change significantly between supine and sitting both in patients and HC. Supine CBF was not different between patients and HC. In contrast, absolute CBF during sitting was lower in patients compared to HC: 474 (96) mL/min in patients and 627 (89) mL/min in HC; p < 0.0001. As a result, percent CBF reduction while seated was −24.5 (9.4)% in severe ME/CFS patients and −0.4 (1.2)% in HC (p < 0.0001). In the ten patients who had no orthostatic intolerance complaints in daily life, the CBF reduction was −2.7 (2.1)%, which was not significantly different from HC (p = 0.58). The remaining 90 patients with orthostatic intolerance complaints had a −26.9 (6.2)% CBF reduction.

No difference in CBF parameters was found in patients with and without fibromyalgia. Patients with a previous diagnosis of postural orthostatic tachycardia syndrome (POTS) had a significantly larger CBF reduction compared with those without POTS: 28.8 (7.2)% vs. 22.3 (9.7)% (p = 0.0008).

Conclusions: A sitting test in severe ME/CFS patients was sufficient to provoke a clinically and statistically significant mean CBF decline of 24.5%. Patients with a previous diagnosis of POTS had a larger CBF reduction while seated, compared to patients without POTS. The magnitude of these CBF reductions is similar to the results in less severely affected ME/CFS patients during head-up tilt, suggesting that a sitting test is adequate for the diagnosis of orthostatic intolerance in severely affected patients.

https://www.mdpi.com/2227-9032/8/4/394

 

[Hoopoe]

That 10 of 90 patients self-reported no significant orthostatic intolerance despite being classified as severe ME/CFS and also had no significant reduction in cerebral blood flow during the test, could be an elegant demonstration that deconditioning is insufficient to explain the reduction in cerebral blood flow or severe ME/CFS.

It also suggests that orthostatic intolerance is not required to have ME/CFS (or that there is one subtype of ME/CFS that doesn't come with OI).

 

[Forbin]

Heart rate and blood pressure did not change significantly between supine and sitting both in patients and HC.

Heart rate and blood pressure was similar between groups during the sitting position, but there was a significant difference in the cerebral blood flow during sitting:

In the present study, a difference close to a significance of 0.05 was found between the sitting systolic blood pressure between healthy controls and severe ME/CFS patients: 122 (18) mmHg for healthy controls and 134 (18) mm Hg for ME/CFS patients. This difference might be explained by the fact that in severe ME/CFS patients, a decrease in blood volume may be present [8,9,10,11].

So blood pressure and heart rate did not change between being supine and sitting in either group, but the initial blood pressure was higher in the ME/CFS group (though not significantly so).

Is the implication that low blood volume in ME/CFS patients is behind the decreased cerebral blood flow? That is, when lying down, low blood volume still produces sufficient cerebral blood flow, but it is insufficient when sitting up? Shouldn't blood pressure and heart rate try to compensate for low cerebral blood flow? Maybe that only kicks in when things become more severe. i.e. when one is standing with low blood volume.

ETA:
If you have low blood volume but also have normal blood pressure could that be the result of constriction of your blood vessels. In other words might the constriction of your blood vessel be sufficient to maintain normal (or here, slightly higher) blood pressure while sitting, but, once you stand up, the blood vessels can't constrict anymore and you get low blood pressure and even lower cerebral blood flow?

 

[beverlyhills]

People that exercise less would have less elasticity in their vessels and thus less perfusion. So you'd have vascular narrowing and low blood volume - not a good combination. For further reading:

Alosco ML, Spitznagel MB, Cohen R, et al. Decreased physical activity predicts cognitive dysfunction and reduced cerebral blood flow in heart failure. J Neurol Sci. 2014;339(1-2):169-175. doi:10.1016/j.jns.2014.02.008

And now the editorial:

In order to correctly perform this study, you would exclude healthy controls and replace them with sedentary controls and, of course, blind the doppler technician to the disease status of the patients, and you would probably want a dropout rate of about 20% instead of like 97,5% of them.

All patients using opiates (opioids induce cerebral vasoconstriction and decrease cerebral blood flow) should be excluded from the cohort. Benzodiazepines and other GABA-modifiers reduce cerebral blood flow, too. Instead, more than 75% of the patients included were on these items.

 

[MSEsperanza]

That seem to me to be very important points, @beverlyhills .

In order to correctly perform this study, you would exclude healthy controls and replace them with sedentary controls

I think I get your point but shouldn't it be sufficient to have healthy controls that are sedentary, not exclude healthy controls altogether?

Ideally, perhaps another control group with patients not only sedentary but bedridden by another illness could be added? The latter could be difficult to recrute, though.